Power train of a marine transport vessel

ABSTRACT

Propellers of a marine transport vessel may be independently controlled at their optimal speed when at least one transmission having a plurality of output shafts capable of independent-speed ratios is connected to an engine and the propellers are respectively mounted at the output shafts of the transmission.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a power train of a marine transportvessel, and more particularly, to a power train that can control aplurality of propellers with various speeds even if only one engine isadopted.

(b) Description of the Related Art

As is well known in the art, various kinds of marine transport vesselsare used for transportation of passengers or cargo on water such aslakes, rivers, and oceans.

Such a marine transport vessel includes an engine for generating powerand a transmission for transmitting the generated power to propellers.Usually, such an engine and a transmission are collectively called apower train. Hereinafter, the term “propeller” is used to include notonly a conventional propeller for generating water current but also anyrotating device for generating a reactive force to a body of the marinetransport vessel. The term “marine transport vessel” is used to mean anymarine vessel that moves by the reactive force of the propeller. In moredetail, the marine transport vessel does not necessarily move on thewater, but it may rather move under the water.

The transmission may be realized in a variety of forms, such as anautomatic transmission or a manual transmission. However, asemi-automatic transmission described in Korean Patent No. 292325 (ofwhich the filing no. is 10-1998-0063295) is very effective.

According to a conventional power train of such a transport vessel, anengine such as an internal combustion engine outputs power (i.e.,torque) through one output shaft and a transmission that receives theoutput torque changes the rotational speed and then transmits it to apropeller. During such a power transmission, only one speed-ratio isrealized.

According to such a conventional scheme of a power train, a powertransmission pattern is very limited since the torque output from anengine having only one output shaft is changed by only one speed-ratioand is then transmitted to the propellers. That is, one engine canoperate one or more propellers only at the same speed.

As a result, the behavior of a marine transport vessel is also limited.For example, for changing the direction of the vessel, rudders to therear of the propellers are operated such that a direction of a reactiveforce is changed and thereby a torque for turning the direction of thevessel is generated. The turning radius of the vessel is consequentlyvery large, as is well known in the art.

When such a turning radius of a vessel is reduced, various merits can beaccordingly achieved. For example, the vessel may turn in a narrowregion and accordingly interference between vessels may be minimized.

In order to provide different torques to different propellers, thevessel may adopt a plurality of engines and a plurality of transmissionsrespectively connected to the engines. However, in this case, torques ofthe separate engines are not easy to harmonize, and a large space isinevitably consumed by the engines and the transmissions.

SUMMARY OF THE INVENTION

Therefore, one object of the present invention is to provide a powertrain of a marine transport vessel that may transmit different torquesat different speed-ratios to a plurality of propellers even if only oneengine is adopted.

In order to achieve such an object, a power train of a marine transportvessel according to the present invention includes: an engine having atleast one output shaft; at least one transmission connected to the atleast one output shaft of the engine, the at least one transmissioncomprising a plurality of output shafts capable of independentspeed-ratios; and a propeller connected to each output shaft of thetransmission.

It is preferable that: the at least one output shaft of the engine isprovided as a plurality; each of the at least one transmission isrespectively connected to each of the plurality of output shafts of theengine; and said each of the at least one transmission comprises aplurality of output shafts capable of independent speed-ratios.

In addition, it is preferable that: the engine comprises a plurality ofpistons for each cylinder; the plurality of pistons for each cylinderreciprocate in a horizontally opposed manner; and the plurality ofpistons for each cylinder are separately connected to the output shaftsof the engine.

It is also preferable that the at least one transmission comprises:first and second drive shafts rotating cooperatively with the outputshaft of the engine; at least one first drive gear and at least onesecond drive gear respectively formed on the first and second driveshafts; and first and second multi-speed mechanisms respectivelyconnected to the at least one first drive gear and the at least onesecond drive gear.

It is further preferable that each of the first and second multi-speedmechanisms comprises a plurality of planetary gearsets, the pluralitycorresponding to a predetermined number of shift-speeds.

In particular, it is preferable that at least one planetary gearset ineach of the first and second multi-speed mechanisms rotates in anopposite direction to at least one other planetary gearset in eachmulti-speed mechanism.

It is preferable that: each of the planetary gearsets comprises a sungear, a ring gear, and a carrier; the ring gear is engaged with acorresponding drive gear among the first and second drive gears; the sungear is connected to the output shaft of the transmission; and each ofthe first and second multi-speed mechanisms further comprises a brakefor selectively stopping the carrier.

In particular, it is preferable that as many drive gears are provided asthere are ring gears in the multi-speed mechanism such that each drivegear is engaged with a corresponding ring gear.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a power train of a marine transportvessel according to an embodiment of the present invention.

FIG. 2 illustrates an exemplary turning strategy of a marine transportvessel by a power train of a marine transport vessel according to anembodiment of the present invention.

FIG. 3 illustrates an embodiment of a length control apparatus used in apower train of a marine transport vessel according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is hereinafter described indetail with reference to the drawings.

FIG. 1 is a schematic diagram of a power train of a marine transportvessel (e.g., a ship) according to an embodiment of the presentinvention.

As shown in FIG. 1, a power train of an embodiment of the presentinvention includes an engine 110. The engine 110 is provided with aplurality of output shafts 113 and 114. Transmissions 120 and 122 arerespectively connected to the output shafts 113 and 114. Thetransmission 120 is provided with a plurality of output shafts 173 and174, and realizes independent speed-ratios therethrough, while thetransmission 122 is provided with a plurality of output shafts 171 and172, and realizes independent speed-ratios therethrough.

As shown in FIG. 1, the engine 110 is a horizontally opposed engine inwhich each cylinder 117 has two pistons 111 and 112 that reciprocate ina horizontally opposed manner, and the two pistons 111 and 112 arerespectively connected to the output shafts 113 and 114 to The left andright pistons 112 and 111 of the engine 110 respectively outputcombustion power of the cylinder 117 to the left and right output shafts114 and 113. The reciprocating motion of the pistons 111 and 112 may besynchronized by a timing device such as a timing belt.

As described above, the left and right output shafts 114 and 113 areconnected to transmissions, each of which has output shafts ofindependent speed-ratios. Since the transmission 122 connected to theleft output shaft 114 and the transmission 120 connected to the rightoutput shaft 113 may be symmetrically realized, the right transmission120 is hereinafter described in further detail.

As shown in FIG. 1, the right transmission 120 includes first and seconddrive shafts 125 and 126 that rotate cooperatively with the right outputshaft 113 of the engine.

First drive gears 131A, 131B, 131C, 131D, and 131R are formed on thefirst drive shaft 125. A first multi-speed mechanism 150 is connected tothe first drive gears 131A, 131B, 131C, 131D, and 131R.

In the same way, second drive gears 132A, 132B, 132C, 132D, and 132R areformed on the second drive shaft 126, and a second multi-speed mechanism151 is connected to the second drive gears 132A, 132B, 132C, 132D, and132R.

A cooperative relationship among the second drive shaft 126, the seconddrive gears 132A, 132B, 132C, 132D, and 132R, the second multi-speedmechanism 151, and the right output shaft 113 is symmetrical to acooperative relationship among the first drive shaft 125, the firstdrive gears 131A, 131B, 131C, 131D, and 131R, the first multi-speedmechanism 150, and the right output shaft 113. Therefore, thecooperative relationship among them is hereinafter described in furtherdetail in connection with the first drive shaft 125.

The rotation of the first drive shaft 125 cooperative with the rightoutput shaft 113 may be realized, as shown in FIG. 1, by an engagementof a gear 140 formed on the right output shaft 113 and gears 141 formedon the first drive shaft 125. In this case, the first and second driveshafts 125 and 126 rotate in the same direction.

Each gear 141 formed on the first drive shaft 125 is realized as a ringgear of a planetary gearset, of which a carrier 142 carrying piniongears is selectively stopped by an external brake 143, and a sun gear(not shown) is fixed to the first drive shaft 125. In this way, a commonspeed-ratio that acts commonly at each shift-speed of the firstmulti-speed mechanism 150 may be achieved. By adopting a plurality ofgears 141 on the first drive shaft 125 and realizing each of the gears141 as a ring gear of a planetary gearset, the common speed-ratio may bepluralized.

In the same way, a common speed-ratio may also be achieved for thesecond multi-speed mechanism 151, and the common speed-ratio of thesecond multi-speed mechanism may also be pluralized.

The first and second multi-speed mechanisms used in an embodiment of thepresent invention may be realized as a shifting device used in asemi-automatic transmission disclosed in the above-mentioned KoreanPatent No. 292325 (filing no. 10-1998-0063295).

As discussed above and as shown in FIG. 1, the second drive gears 132A,132B, 132C, 132D, and 132R, and the second multi-speed mechanism 151 arestructured symmetrical to the first drive gears 131A, 131B, 131C, 131D,and 131R, and the first multi-speed mechanism 150. Therefore, the firstdrive gears 131A, 131B, 131C, 131D, and 131R, and the first multi-speedmechanism 150 are hereinafter described in further detail.

The first multi-speed mechanism 150 includes planetary gearsets 160A,160B, 160C, 160D, and 160R, the number of which is as many as apredetermined number of shift-speeds thereof. FIG. 1 exemplarilyillustrates four forward shift-speeds and one reverse shift-speed, butthe number of the forward/reverse shift-speeds may be altered obviouslyby a person of ordinary skill in the art. In particular, although onlyone reverse shift-speed is illustrated in FIG. 1, the reverseshift-speed may also be pluralized to as many as or a different numberfrom the forward shift-speeds. As is well known in the art, oneplanetary gearset has three operational elements of a sun gear, a ringgear, and a carrier. Therefore, when a torque is input through oneelement of the three and another element is fixed (i.e. rotation thereofis stopped), the torque is output through a remnant element.

In the same way, planetary gearsets 160A-160R used in the firstmulti-speed mechanism 150 of an embodiment of the present inventionrespectively include sun gears (not shown), ring gears 161A-161R, andcarriers 162A-162R. The ring gears 161A-161R are respectively engagedwith the drive gears 131A-131R, and the sun gears (not shown) arefixedly connected to the output shaft 173 of the right transmission 120.In addition, the first multi-speed mechanism 150 of an embodiment of thepresent invention further includes brakes 163A-163R for selectivelystopping the carriers 162A-162R. By constructing input elements andoutput elements as such, the structure of the multi-speed mechanism maybe simplified.

As is known in the art, a speed-ratio of a planetary gearset may bealtered by changing a ratio of a radius of a sun gear to a radius of aring gear. Therefore, diameters of the drive gears 131A-131R are notnecessarily different but may be realized as one diameter value. Thatis, as is disclosed in the above-mentioned Korean Patent No. 292325,different speed-ratios may be achieved by stopping carriers of differentplanetary gearsets included in the multi-speed mechanism 150 whiletorque is transmitted to the ring gears 161A-161R of the planetarygearsets 160A-160R through one drive gear.

However, more preferably, as shown in FIG. 1, a wider range ofspeed-ratios may be achieved by transmitting torque to the planetarygearsets 160A-160R through respective drive gears 131A-131R.

The brakes 163A-163R for selectively stopping the carriers 162A-162R areobvious to a person of ordinary skill in the art or from the disclosureof the above-mentioned Korean Patent No. 292325.

When a carrier (e.g., 162B) of a planetary gearset (e.g., 160B) includedin the first multi-speed mechanism 150 is stopped by an operation of abrake (e.g., 163B), the torque is changed by a speed-ratio determined bya specification of the planetary gearset (i.e., 160B) that has itscarrier (i.e., 162B) fixed, and the changed torque is output through theoutput shaft 173 of the first multi-speed mechanism 150. Therefore, apropeller 183 connected to the output shaft 173 rotates and generateswater current, and thereby a vessel 100 moves by a reactive force of thewater current.

The sun gear (not shown) of the planetary gearset 160R among theplanetary gearsets 160A-160R used in the multi-speed mechanism 150rotates, when its carrier 163R is stopped, in an opposite direction inwhich sun gears (not shown) of other planetary gearsets 160A-160D rotatewhen their carriers 162A-162D are stopped. That is, the planetarygearset 160R outputs torque reverse to that of the other planetarygearsets 160A-160D.

Such a function may be realized in a variety of schemes, for examplethrough a different number of pinion gears in the reverse planetarygearset. In addition, an idle gear 165 may be disposed between the ringgear 161R and the driver gear 131R, as shown in FIG. 1.

According to the above scheme of a power train, the vessel 100 has fourpropellers 181, 182, 183, and 184 connected to one engine 110, and eachof the propellers 181, 182, 183, and 184 may have a different rotationspeed because of the transmissions 120 and 122. In particular, somepropellers may rotate reversely to other propellers.

Therefore, for example, when a leftmost propeller 181 of the vessel 100is reversely operated and a rightmost propeller 184 is normallyoperated, the rightmost propeller 184 exerts a forward propulsive forceto the vessel 110, and the left most propeller 181 exerts a rearwardpropulsive force thereto. So, a rotating torque is generated around thevessel body, and therefore, the vessel 100 may rotate at its stationaryposition without requiring a large turning radius.

When rudders 191, 192, 193, and 194 are provided at the rear of thepropellers as shown in FIG. 1, such a rotation of a vessel 100 becomeseasier. That is, as shown in FIG. 2, by positioning the rudder 194 atthe rear of the right propeller 184 and the rudder 191 at the rear ofthe left propeller 181 in opposite directions, rotating torquesgenerated by the propellers may be maximized. Positioning of ruddersshown in FIG. 2 may be variously altered by a person of ordinary skillin the art.

For a better preferable embodiment of the present invention, as shown inFIG. 1, the horizontally opposed engine 110 is provided with outputshafts 115 and 116 extending to a front of the marine transport vessel100, symmetrically to the output shafts 113 and 114 to the rear of themarine transport vessel 100. The output shafts 115 and 116 arerespectively connected to transmissions 124 and 123 that are structuredthe same as the previously-described transmissions 120 and 122.

The transmission 124 is provided with a plurality of output shafts 175and 176, and realizes independent speed-ratios therethrough. Thetransmission 123 is provided with a plurality of output shafts 177 and178, and realizes independent speed-ratios therethrough.

Propellers 185, 186, 187, and 188 are respectively connected to frontends of the output shafts 175, 176, 177, and 178, and they are enclosedin the vessel body. That is, the propellers 185, 186, 187, and 188 arerespectively contained in containing cavities 215, 216, 217, and 218formed at the vessel body

Covers 195, 196, 197, and 198 are formed along a surface of the vesselbody in front of the propellers 185, 186, 187, and 188 such that a frontsurface of the vessel body is normally smooth. The containing cavities215, 216, 217, and 218 seal the output shafts 175, 176, 177, and 178such that water does not leak into the vessel body when the covers 195,196, 197, and 198 are open.

Length control apparatus 205, 206, 207, and 208 are respectively formedat the output shafts 175, 176, 177, and 178 for enabling changing oflengths thereof. In order to rotate the propellers 185, 186, 187, and188, the covers 195, 196, 197, and 198 are opened and the length controlapparatus 205, 206, 207, and 208 are operated such that the outputshafts 175, 176, 177, and 178 are elongated. Accordingly, the propellers185, 186, 187, and 188 protrude to the exterior of the vessel body andare then rotated. The length control apparatus 205, 206, 207, and 208may be realized in a variety of fashions by a person of ordinary skillin the art. Hereinafter, an embodiment of the length control apparatus205 formed at the output shaft 175 is described with reference to FIG.3. From the following description with reference to FIG. 3, the lengthcontrol apparatus 206, 207, and 208 formed at other output shafts 176,177, and 178 will be obviously understood by a person of ordinary skillin the art.

As shown in FIG. 3, the output shaft 175 is divided into upper and loweroutput shafts 310 and 305, and they are spline-engaged with each other.Therefore, the lower and upper output shafts 305 and 310 may relativelymove in a vertical direction in FIG. 3.

For such a relative movement, a bearing 320 is mounted on an exteriorside of the upper output shaft 310, and an exterior side of the bearing320 is connected, by a belt 335, to a motor 340 fixed at the containingcavity 215. The belt 335 may smoothly operate by roller bearings 330 and332 fixed in the containing cavity 215 at positions above and below themotor 340.

Therefore, when the motor 340 is operated, a total length of the outputshaft 175 becomes changed in accordance with an operating direction ofthe motor 340.

By such a preferable embodiment of the present invention, i.e., bydisposing a plurality of propellers forwardly to the vessel body, themarine transport vessel 100 may decelerate more rapidly, and it may alsomove in a reverse direction. Furthermore, a turning radius thereof maybe further reduced.

In addition, the covers normally cover the propellers (i.e., thecontaining cavities) such that an influence on an outline of the vessel100 is minimized. Therefore, in normal forward sailing, friction withwater is minimized.

For a reverse movement or a rapid deceleration of the vessel 100, thecovers are opened, and the propellers protrude exterior to the vesselbody by extending due to operation of the length control apparatus. Inthis state, the propellers rotate, so that the vessel body can rapidlydecelerate or move rearwardly.

In addition, the transmissions 123 and 124 connected to the propellersat the front of the vessel body may be respectively shifted to reverseranges, and the front propellers may also have different speeds andthereby provide easier rotation of the vessel body.

When rotation speeds and directions of front and rear propellers of thevessel are optimized, the turning radius of the vessel is furtherreduced and the turning speed is further enhanced, as is obvious to aperson of ordinary skill in the art.

According to an embodiment of the present invention, a plurality ofpropellers are respectively operated at their optimal speeds even ifonly one engine is provided at a vessel, so the performance of thevessel may be enhanced.

In addition, when the engine has a plurality of output shafts, thenumber of propellers that can be optimally controlled may beequivalently increased.

Furthermore, each propeller is optimally controlled since separatetransmissions are provided to output shafts of the engine, and eachtransmission controls its output shaft with independent speed-ratios.

A clutching function is realized by a multi-speed mechanism included inthe transmission, so an additional clutch device for controlling powertransmission from an engine to propellers is not needed. Therefore, apower train of a vessel may be simplified.

Since the engine is realized as a horizontally opposed engine, theheight of a mass center of a power train may be lowered, and thereby thestability of a vessel body may be enhanced.

Since each propeller may be controlled at a speed independent fromothers and at least one propeller may be reversely rotated, turningradius of the vessel body is reduced.

Since the propellers may reversely rotate under the power of the engine,the vessel may decelerate, using the power of the engine, more rapidlythan conventional marine transport vessels that only decelerate byfriction with water.

While this invention has been described in connection with a preferredembodiment, it is to be understood that the invention is not limited tothe disclosed embodiments, but, on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims.

Throughout this specification and the claims which follow, unlessexplicitly described to the contrary, the word “comprise” or variationssuch as “comprises” or “comprising” will be understood to imply theinclusion of stated elements but not the exclusion of any otherelements.

1. A power train of a marine transport vessel comprising: an enginehaving at least one output shaft; at least one transmission connected tothe at least one output shaft of the engine, the at least onetransmission comprising a plurality of output shafts capable ofindependent speed-ratios; and a propeller connected to each output shaftof the transmission.
 2. The power train of claim 1, wherein: the atleast one output shaft of the engine is provided as a plurality; each ofthe at least one transmission is respectively connected to each of theplurality of output shafts of the engine; and said each of the at leastone transmission comprises a plurality of output shafts capable ofindependent speed-ratios.
 3. The power train of claim 1, wherein: theengine comprises a plurality of pistons for each cylinder; the pluralityof pistons for each cylinder reciprocate in a horizontally opposedmanner; and the plurality of pistons for each cylinder are separatelyconnected to the output shafts of the engine.
 4. The power train ofclaim 1, wherein the at least one transmission comprises: first andsecond drive shafts rotating cooperatively with the output shaft of theengine; at least one first drive gear and at least one second drive gearrespectively formed on the first and second drive shafts; and first andsecond multi-speed mechanisms respectively connected to the at least onefirst drive gear and the at least one second drive gear.
 5. The powertrain of claim 4, wherein each of the first and second multi-speedmechanisms comprises a plurality of planetary gearsets, the pluralitycorresponding to a predetermined number of shift-speeds.
 6. The powertrain of claim 5, wherein: each of the planetary gearsets comprises asun gear, a ring gear, and a carrier; the ring gear is engaged with acorresponding drive gear among the first and second drive gears; the sungear is connected to the output shaft of the transmission; and each ofthe first and second multi-speed mechanisms further comprises a brakefor selectively stopping the carrier.
 7. The power train of claim 5,wherein at least one planetary gearset in each of the first and secondmulti-speed mechanisms rotates in an opposite direction to at least oneother planetary gearset in each multi-speed mechanism.
 8. The powertrain of claim 6, wherein as many drive gears are provided as there arering gears in the multi-speed mechanism such that each drive gear isengaged with a corresponding ring gear.
 9. The power train of claim 2,wherein the plurality of output shafts of the engine comprise outputshafts extending forward and rearward from the engine with respect to avessel body.
 10. The power train of claim 9, wherein the output shaftextending forward from the engine with respect to the vessel body isadjustable in its length.
 11. The power train of claim 10, furthercomprising a front propeller connected to the output shaft extendingforward from the engine with respect to the vessel, wherein the frontpropeller is contained in a containing cavity inwardly formed at thevessel body, and a cover is provided at a vessel body side end of thecontaining cavity.